Excel WEIBULL Function

Description

The Excel WEIBULL function returns the Weibull probability density function or Weibull cumulative distribution for a supplied set of parameters. It is frequently used for reliability analysis, e.g., for testing the mean time of the failure of an equipment in a specific time range.

Note: This function has been replaced with one or more new functions that may provide improved accuracy after Excel 2010 version. This function is still can be available but considering it may be not available in the future, you should better study to use the new function from now.

Formula syntax

Arguments

Returns

WEIBULL function returns a numeric value.

Remarks

1. The function returns #VALUE! error value if x, alpha, or beta is a non-numeric value.

2. The function returns #NUM! error value when

• x is negative;
• alpha or beta ≤ 0
• X_range and prob_range have different numbers of data points, WEIBULL function return the #N/A error value.

3. The equation for Weibull cumulative distribution function is

4. The equation for Weibull probability density function is

5. When alpha = 1, WEIBULL function returns the exponential distribution with

Version

Excel 2007 and earlier versions

Usage and Examples

Basic usage

For getting the Weibull cumulative distribution function (cumulative as TURE) and Weibull probability density function (cumulative as FALSE) separately for the supplied x (10), alpha (15),beta (20), you can use the WEIBULL function as these:

=WEIBULL(10,15,20,TRUE) // Weibull cumulative distribution function

=WEIBULL(10,15,20,FALSE) // Weibull probability density function

Press Enter key to get the result.

Other Functions:

• Excel POISSON Function
  The Excel POISSON function returns the Poisson distribution which is used to predict the number of events occurring over a specific time.

• Excel FDIST Function
  The Excel FDIST Function returns the (right-tailed) F probability distribution which is usually used to measure the degree of diversity between two data sets.

• Excel EXPON.DIST Function
  EXPON.DIST function used in Excel 2010, returns the exponential distribution based on the given x value and the parameter of the distribution.

• Excel F.DIST Function
  The Excel F.DIST function returns the F probability distribution which is usually used to measure the degree of diversity between two data sets.